3.3 Pathways through which warming and N addition influenced species dominance
Structural equation modeling allowed us to disentangle the contributions of the direct and indirect effects of warming and N addition on plant phenology and dominance. The analyses suggested that soil temperature and moisture at different soil depths played key roles in determining the flowering phenology of all the studied species (Figure 3). For C3 plants, S. breviflora, A. tenuissimum andC. ammannii , the duration of flowering decreased with increasing soil temperature, causing declines in plant dominance. For C4 plants, C. songorica and K. prostrata , flowering phenology was largely determined by soil moisture. Nitrogen addition prolonged the duration of flowering via increasing soil moisture, consequently leading to an increase in the dominance of C4 plants (Figure 3).